A dispenser for injecting a certain material such as a caulking agent or the like by actuating a trigger to squeeze a storing portion after it is once stored in the storing portion, in order to fill gaps or cracks arising inside/outside of a building with the foregoing material has been hitherto used (refer to an official gazette of, e.g., Japanese Patent Laid-Open Publication NO. 51-115718).
Trials have been made for practically employing a dispenser of the foregoing type as a cooking instrument for the purpose of injecting an edible viscous material such as mayonnaise, cream or the like. In recent years, especially, when mayonnaise is distributed over a number of dishes each having salad or the like placed thereon in a restaurant or the like, a dispenser including a cartridge molded of a thin sheet of synthetic resin by employing a blow molding process in consideration of easy exchanging of the present viscous material with other type of viscous material is increasingly employed as a cooking instrument. This type of dispenser is practically used by squeezing the cartridge with an operator's hand after the cartridge is once filled with the viscous material.
However, with respect to the cartridge having a small thickness as mentioned above, when the inner diameter of a storing portion for holding the cartridge is dimensioned to be equal to the outer diameter of an extrusion plate, there arise malfunctions that a bottom of the cartridge is infolded between the extrusion plate and the inner wall surface of the storing portion, resulting in the extrusion plate failing to be displaced further in the forward direction, and moreover, a part of the viscous material remains in the infolded Dart of the cartridge, resulting in the viscous material failing to be completely injected from the cartridge.
Even in case that no infolding occurs with the cartridge, it is observed that the outer peripheral surface of the cartridge comes in close contact with the inner wall surface of the storing portion with the result that the extrusion plate is hardly displaced in the squeezing direction.
To solve these problems, a proposal has been made with respect to a dispenser as disclosed in an official gazette of, e.g., Japanese Utility model Publication NO. 64-1270 wherein a container having a viscous material contained therein is received in an outer bag adapted to be slidably displaced so that the container can smoothly be compressed via the outer bag. However, this proposal is not practically employed due to an expensive cost because the container is produced by way of complicated steps, and moreover, it is a disposable container.
In addition, it is undesirably necessary from the viewpoint of structure that the dispenser is actuated with a large magnitude of actuating force. Since a viscous material contained in the container is not injected at a constant rate, there arises another malfunction that the viscous material can not exactly be injected through an injecting hole at a constant rate with the dispenser. Further, there appear problems that the injected viscous material is not sharply cut off from the container, and a part of the viscous material remains still in the vicinity of an injection port or the injection port is unsanitarily clogged with the remaining viscous material.
The present invention has been made in consideration of the foregoing background and its object resides in providing a dispenser for injecting a viscous material wherein an extrusion plate is smoothly displaced without incorrect operation of the dispenser due to infolding of a cartridge, and moreover, the dispenser can easily be handled with an operator's hand.
Here, a purport of the present invention consists in a dispenser employable as a cooking instrument. However, due to the fact that the foregoing type of dispenser is originally designed for industrial use, components other than a cartridge are made of a metallic material in view of durability and other subjects. Thus, the dispenser itself becomes heavy, resulting in the dispenser being handled with difficulty. In addition, since part of a thrusting portion (rod) is exposed to the outside, when the dispenser is employed as a cooking instrument in a restaurant or the like in which an ample amount of water is consumed in a cooking shop, the components readily rust, causing an unsanitary problem to appear.
To solve this problem, a common applicant to the present invention proposed a manual type dispenser for injecting a viscous material wherein the viscous material contained in a storing portion is extruded by actuating a trigger disposed in a main body as disclosed in Japanese Utility Model Application NO. 2-60866 (Japanese Patent Laid-Open Publication NO. 3-105486). This proposed manual type dispenser includes as essential components a gear wheel assembly mounted on a support shaft for a trigger in the coaxial relationship, a pawl member disposed on the trigger to be brought in and out of meshing engagement with the gear wheel assembly, a resilient member for thrusting the pawl member in the direction of meshing engagement with the gear wheel assembly, a rod meshing with the gear wheel assembly so as to be reciprocably displaced in a storing portion having an injection hole formed at the foremost end thereof, a stopper disposed in the main body so as to allow it to be brought in and out of meshing engagement with the gear wheel assembly, and a resilient member for thrusting the stopper in the direction of meshing engagement with the gear wheel assembly.
With respect to the proposed manual type dispenser, however, many requests have been raised from users so as to enable the rod to be easily retracted when the viscous material is supplemented with a new viscous material or exchanged with other kind of viscous material after completion of an injecting operation performed for the viscous material.
In view of these requests, another object of the present invention is to provide a dispenser for injecting a viscous material wherein the dispenser is constructed based on the previously proposed dispenser in order to assure that after the trigger is released from the actuated state, the pawl member is reliably disengaged from the gear wheel assembly and wherein the aforementioned problems are completely eliminated and practical convenience of the dispenser is substantially improved.